Electromagnetic bell



Patented Aug. 18, 1931 UNITED STATES PATENT OFFICE LOUIS E. RICHMOND, OF SHELBY, OHIO, ASSIGNOR TO THE AUTOCALL COMPANY, OF

SHELBY, OHIO, A CORPORATION OF OHIO ELECTROMAGNETIC BELL Application filed 0ctober3, 1925. Serial No. 60,141.

In electric bell construction, it has long been recognized that a solenoid type of actuation would offer considerable advantages from a mechanical standpoint, but the development of this type has been hindered by the low electrical efiiciency heretofore se-.

cured. In particular, where such a device was used on an alternating current circuit, it was found that the power factor on the line was reduced to a serious extent, and operation was unsatisfactory.

Among the features of the present invention is the provision of a simple and readily accessible construction and an electromagnetic unit allowing alternating current operation, and series or other installation as desired.

To the accomplishment of the foregoing and related ends, the invention, then, consists of the means hereinafter fully described, and particularly pointed out in the claim, the annexed drawings and the following description setting forth in detail one form of construction exemplifying my invention, such disclosed construction constituting however, but one of various applications of the principle of my invention. 1

In said annexed drawings Fig. 1 is a vertical sectional View of such device; Fig. 2 is a detail section of theplunger taken on the plane indicated by the line IIII, Fig. 1; Fig. 3 is a detail section taken on the plane indicated by the line III-III, Fig. 1; Fig. 4 is a plan view of a blank from which the plunger may be fashioned; Fig. 5

is a detail sect-ion taken on the plane indicated by the line V-V, Fig. 1; and Fig. 6 is a vertical section similar to Fig. 1 but on reduced scale, showing the provision for interchangeable sounding elements. i

Broadly speaking, the device may be sai to comprise an electromagnetic unit and a sounding element, and in practical construction it is preferred to mount these in cooperative relation on a base 1, which may be drilled for attachment to a wall, an outlet box or other desired location, and which may have conduit connections as desired. A magnet spool or core 2 of bakelite or other desirable material carries an insulated wire winding 4 between the spool heads 3 and is supported in position by an upper bracket 5 and a lower bracket 6. The lower bracket includes a clamping member 7 which is attached to the member 6 by a screw or other desired means and each of the said brackets are in turn secured to the base by screws or bolts. At the lower end of the core, a stop screw 14 is carried by a support-arm 12 suitably secured to the base and in order to obtain a locking adjustment on such'screw, I prefer to form the supportarm 12 with a recurved or U shaped end 13, the screw being threaded therein as seen. A cushioning means C such as of felt, rubber or the like, may be interposed between the stop screw 14 and the solenoid plunger 8 which is arranged for reciprocable motion in the solenoid core. This plunger 8 is made hollow and I prefer to fashion it from a sheet metal blank B (see Fig. 4) of suitable magnetic metal, the blank being slotted as at S for the reception of spider or skeleton support elements 9 which in turn carry a tapper 10. The blank B being fashioned into hollow form as seen for instance more clearly in the sectional view of Fig. 3, it is assembled with the spider or skeleton support element 9, this being engaged in the slots as seen and in turn carrying the tapper 10. The securing of all of these together may be accomplished by soldering, brazing or other convenient means and it is desirable also to further strengthen the construction by a rivet as at 11. Enclosing the electromagnetic unit, a sounding-element support 15 forming in effect also a cover is arranged in an easily movable manner, preferably as by pivoting to the base member 1. An effective mounting, for instance, is a hinge as shown at 16 and an additional or auxiliary fastening means may be provided at a point opposite thereto asfor instance a clamping screw or bolt 20. A sounding-element or gong 17 is then in turn mounted upon such support 15 as by a cap screw l8, a spacing washer 19 conveniently being interposed. In order to prevent an access of rain or dirt, etc. to the interior of the device through the t apper opening in the housing,

it is desirable also to provide a hood or protective plate 23 over the edge of the gong. This would be preferably secured to the support 15 by screws.

In order to allow of interchanging the sounding-elements, an extension support 21 may be secured to the housing or support member 15 as for instance by cap screw 22 and by reason of the threaded holes 24, gongs or sounding-elements of various size can then be mounted on such extension element without necessitating the disturbing of the remainder of the assembly. In fact, as will be seen, the device allows of conveniently raising the sounding-element and cover as a whole so as to permit access to the electromagnetic unit without thereby disturbing the working position ofthe device or its adjustment, and if a greater freedom of accessibility is necessary the hinge pin 16 may be removed and thus the entire gong and support be withdrawn. from the base.

From the foregoing, the operation of the device will be readily understood. Current of any desired character and quantity being supplied to the magnet winding, the magnet is energized and the plunger 8 is thrown into striking engagement with the soundingelement or gong as shown in the extreme dotted line position in Fig. 1. On re-coil, the plunger comes to rest against the cushioning element C. By virtue of the adjustable stop screw 14, the length ofstroke may be set-as desired and at the same time the cushioning element will prevent any undesirable hammering and vibration detrimental to the device as a Whole. In the use of alternating current, as will be seen, the amount of magnetic metal exposed in the field is so relatively small that the power factor in'the circuit is but slightly reduced, and the maximum magnetic saturation of the plunger is moreover obtained with very little current. Also high resistance windings become perfectly feasible. Direct current may of course also be used, and in certain installations, the device is on closed circuit for considerable intervals. In such case, the plunger will assume a position as indicated by the intermediate dotted line in Fig. 1. By reason of the light weight of the plunger and the ab sence of a piston or suction effect when in action, due to the hollow construction, the use of large units on battery circuits becomes economical.

Other forms may be employed embodying the features of my invention instead of the one here explained, change being made in the form or construction, provided the elements stated by the following claim or the equivalent of such stated elements be employed.

I therefore particularly point out and dis tinctly claim as my invention:

In a device of the character described, a

ber, 1925.

LOUIS E. RICHMOND.

r securing the tapper to 

